The invention relates to a process and an apparatus for the production of a flowable mixture which reacts to form foam from flowable components stored in storage containers. Prior to the metered introduction into a mixing zone at least one of the components is charged with a defined amount of gas by introducing this component and gas separately into a gasification chamber equipped with a hollow stirrer. If gas is required, the gas is sucked in by the hollow stirrer through the hollow shaft thereof, is stirred into the component and is finely divided therein until the desired value is achieved.
With an apparatus of this general type (U.S. application Ser. No. 550,428, filed on Nov. 10, 1983 now abandoned; German Offenlegungsschrift 32 44 037), gasification is carried out in the storage container or in a smaller intermediate container. The air is sucked in by the hollow shaft inside the container directly from the gas space. The suction opening of the hollow shaft is thus located beneath the lid inside the gas space. The density measuring device switches on the stirrer mechanism by means of a control device in order to stir in gas when the lower tolerance threshold of the desired density value is exceeded, and switches it off again when the upper tolerance threshold is reached. This arrangement has the disadvantage that the stirrer mechanism can no longer be used for homogenizing the component located in the container because it is and must be switched off from time to time.
Segregation then occurs in the case of components containing additives which tend to settle. Continuous circulation is also important for keeping the temperature uniform.
The object of the present invention was to improve the apparatus in such a way that components containing additives which tend to settle and components which have to be kept at a uniform temperature can be circulated continuously for the purpose of homogenization.